Nazi submarine with entombed crew found off North Carolina

Underwater researchers have revealed the first images seen of a sunken German submarine ever since it was presumably sunk by American planes and a merchant freighter during desperate days in 1942. The U-576 Kriegsmarine U-boat was on a mission to destroy Allied shipping along the Atlantic coast during the early days of the Second World War. It managed to sink the Nicaraguan-flag SS Bluefields merchant ship but was in turn sunk, taking down all 45 hands onboard.

Sonographic image of U-576 from 2014

The underwater expedition was intended to map the area near Cape Hatteras off the North Carolina shore. This discovery is the only known location in U.S. waters that contains archaeologically preserved remains of a convoy battle where both sides are so close together. Joe Hoyt, Monitor National Marine Sanctuary archaeologist and chief scientist for the expedition said of the find, “By studying this site for the first time, we hope to learn more about the battle, as well as the natural habitats surrounding the shipwrecks.”

U-576 underway

Almost 1,600 Allied sailors, including 1,100 merchant mariners, died off North Carolina during the Second World War. Most of them perished in 1942 when Nazi submarines could easily destroy Allied ships that were inadequately protected by naval forces. It became known as the “Battle of the Atlantic.” The wrecks of the U-576 and the Bluefields off Cape Hatteras were about 240 yards apart and 750 feet below the surface. They had been previously detected and viewed only by sonar when they were discovered in 2014.

SS Bluefields

David Alberg, superintendent of the Monitor National Marine Sanctuary in Virginia said that because the submarine’s dive planes were tilted upwards, and that the hatches were still sealed, he concluded that the submarine contains the bodies of all the German crewmembers who perished while seeking to save their lives.

U-576 conning tower

The expedition launched its first dives with mini-submarines on August 24. The National Oceanic and Atmospheric Agency and the University of North Carolina are working with the assistance of the nonprofit Project Baseline, which provided the research vessel and the two mini-subs.

The expedition had to return to port in Beaufort on August 29 because of heavy seas of the sort that have swamped thousands of ships over the centuries on the Outer Banks. Researchers hope to return later. Alberg said that while the group has obtained significant amounts of data, he hopes that the next voyage will produce more.

The mini-subs and an unmanned submersible vehicle took photographs that will be used to produce three-dimensional models. They also did laser scans to produce precisely detailed images and used sonar to sweep the ocean bottom and water column around the wrecks. The data will generate a 3D rotating model of the battle site that will be available online.

2G Robotics and SRI International provided submersible robots and remote-sensing technology. The Coastal Studies Institute of the University of North Carolina will create the three-dimensional models of the wrecks.

Alberg said that among the mysteries surrounding the wreck is the reason for its sinking. He also wondered out loud, "What were the last minutes for the crew like?”

A preliminary analysis shows that despite being targeted by depth charges dropped by U.S. Navy warplanes and being swept with machine gun fire from a merchant ship in the convoy, the U-boat shows no outward sign of damage.

The conning tower is intact, and the word 'Peterle' can be seen painted on the sub. The wooden deck has rotted away.

NOAA is now considering proposals to expand the Monitor National Monument to cover other offshore World War II wrecks, thus limiting diving and other exploration. Under international maritime law, the wreck of the U-576 remains the property of the German government. A recommendation could emerge in late winter or early spring as to how the area around Cape Hatteras will be designated.

Nazi Germany’s state-of-the-art submarines “Unterseebooten” were extremely successful along the Atlantic Coast during the first year of the worldwide war. The area became known as "Torpedo Junction" because of the hundreds of vessels that foundered there. The U-boats used the offshore environment off Cape Hatteras and the Outer Banks to their advantage.

The U-576 was built in Hamburg at the Blohm & Voss shipyards. It was skippered by Capt. Lt. Hans-Dieter Heinecke and was on its fourth tour. It set out from the Nazaire sub base in France in June 1942 and headed towards North America. Along the way, it was damaged by an aircraft attack on July 12 or 13 and signaled that it would head east because repairs could not be accomplished onboard by the crew. But on July 15, the U-576 encountered Convoy KS-520. The convoy consisted of 19 merchant ships and five escorts and was headed from Hampton Roads, Virginia, to Key West, Florida.

The German sub fired four torpedoes, one of which struck and destroyed the SS Bluefields. Another hit and damaged the U.S. cargo ship Chilore, while the remaining torpedos struck the Panamanian-flag tanker J. A. Mowinckel, damaging her. All hands onboard the Bluefields survived.

After unleashing its torpedoes, the U-576 unintentionally surfaced in the middle of the convoy, prompting one of the convoy′s ships, the SS Unicoi, to open fire on her. It was then that two United States Navy Vought OS2U Kingfisher aircraft attacked the submarine with depth charges. One of the depth charges landed on the deck of the submarine but then rolled overboard before exploding. Subsequently, the U-576 sank, leaving a large pool of oil on the surface of the sea. There were no visible survivors.